The clinical assessment of concussion and determination of recovery has undergone remarkable enhancements over the past 30 years (1–6). While post-concussion symptom evaluation continues to be a crucial component (1), clinical evaluation of concussion has evolved to include a variety of tests that now embrace static and dynamic balance, cognitive functioning, oculomotor performance, vestibular functioning, and dual-task proficiency (7, 8). Furthermore, the implementation of a graduated return-to-sport (RTS) strategy has become an essential component of concussion management (1). This strategy involves a graded escalation in physical exertion; the progression through which requires the absence of symptom exacerbation, in accordance with the 2023 Consensus Statement on Concussion in Sport (1).

One significant limitation of our current understanding of RTS following a concussion is the need for universally accepted thresholds for intensity (i.e., heart rate [HR]), type and complexity of movement, and duration of activity required within each stage of the RTS strategy. Presently, providers and patients primarily rely on the subjective response to exertional stressors to guide progression through the various stages. Healthcare professionals must also make decisions based on their patients’ recall during each step of the RTS strategy in order to inform further RTS recommendations.

Clinical tests have been developed to mitigate these limitations, purporting to offer a more comprehensive and objective evaluation with consideration of athletic-specific contexts. These tests necessitate the concurrent execution of motor (i.e., physical) tasks with visual or cognitive tasks. These multifaceted “dual-task” testing paradigms have demonstrated a capacity to identify performance deficits potentially overlooked by conventional single-domain clinical measures (9, 10). However, it is essential to underscore that the psychometric properties (e.g., reference norms, test-retest reliability) of these dual-task assessments, as well as the standardization of testing procedures across divergent age groups and cultural norms, have not yet been definitively established (11, 12).

While dual-task tests offer a more accurate approximation of the movements and complexities inherent in sport, there are still limitations as the motor elements employed in such tests typically involve a gait or balance task conducted within a single plane of movement, whereby sports often necessitate multi-planar movements, rotations, and accelerations. Both the Gapski-Goodman Test (GGT) (13) and the Dynamic Exertion Test (EXiT) (14), have bridged this gap by amalgamating sensory, motor, and cognitive components. Both of these tests involve an aerobic exercise component and a plyometric/dynamic circuit protocol (13, 14). When these tests are incorporated within the post-concussion medical clearance assessment, they have demonstrated efficacy in identifying a subset of individuals prone to symptom exacerbation (13, 14). Notably, Marshall et al. (13) found that 14.6% of participants experienced symptom provocation during the GGT or the modified GGT, while Kochick et al. (14) observed that 6.6% of patients exhibited symptom provocation on EXiT.

Despite the significant strides made in concussion management from the utilization of dual-task tests, resource constraints such as the reliance on expensive equipment (i.e., treadmill or stationary bike), extensive spaces, and specialized clinician expertise limit their generalizability. To help address these potential barriers, our objective was to develop a test with minimal resource requirements encompassing key essential elements of sport/physical activity, including HR elevation, multi-planar movement, and multi-tasking; all executable within a limited space such as a doctor’s office. The ultimate goal is to develop and validate a generalizable, accessible, user-friendly, and multimodal physical exertion test that captures the key elements of sport participation. By accurately reflecting the multifaceted demands of sport participation, this test is designed to serve as a robust tool in aiding practitioners in the decision-making process for medical clearance, thereby facilitating a safe and informed return to sport for athletes post-concussion. To that end, it is imperative to first ascertain the response of healthy athletes to the Multimodal Exertional Test (MET) to ensure that the test can effectively elicit increases in HR while maintaining symptom provocation to a minimum. Therefore, the purpose of this study was to assess HR responses and associated symptoms at each stage of the MET protocol within a group of healthy interuniversity athletes, thereby establishing a foundational understanding of physiological and symptom responses during exertion.

The Multimodal Exertional Test (MET) was successfully piloted on healthy interuniversity athletes, demonstrating its ability to incrementally increase and maintain increased HRs across stages without provoking symptoms. Notably, HR increases were observed from pre-MET to Stage 1, and then between Stages 3 to 4, aligning with the expected physical demands of these stages. Female participants exhibited higher HR throughout, indicating a potential sex difference in cardiovascular response during the MET protocol. Minimal symptom provocation supports the protocol’s safety and provides a normative benchmark for symptom levels in healthy, uninjured athletes.

We monitored average and maximum HR across different stages of the MET protocol. Initial observations indicated that Stages 1 and 4 notably increased HR among participants, likely reflecting a progression from rest to activity in Stage 1, and then an intensification of cardiovascular exertion during Stage 4 through plyometric exercises. The consistent heart rates observed across Stages 1 to 3 were not surprising, as these stages aimed to increase head movement and cognitive load rather than cardiovascular demand.

We observed sex-specific differences in HR response: females exhibited higher and more varied HR than males. These preliminary observations underscore the inherent differences in cardiovascular physiology between sexes (34), and one explanation for these differences may be due to the impact of hormonal variations between sexes, specifically from menstrual cycle or contraceptive use (35, 36). Although the limited sample size precluded a thorough exploration of sex-based disparities, these results provide an intriguing direction for future field testing of the MET protocol.

Understanding how the MET impacts symptom burden in healthy athletes is crucial for differentiating between concussion-related symptoms and those arising from normal physical exertion. Our findings indicate minimal symptom provocation during the MET across all participants, with modelled average symptom severity score estimates prior to the MET and throughout all tasks and stages of approximately 5 for males and 6 for females. These estimates are aligned with prior work in healthy athletes (37), as it is common for individuals to report some symptoms owing to fluctuations in daily stress and well-being. The lack of variation in symptom burden across the MET led to expected degeneracies in our statistical modelling; a larger sample and greater detail of participant information will likely overcome this issue and improve future estimates. However, the consistency of symptom scores holds significant clinical relevance, as it will assist us in identifying clinical cut points for test stoppage and can assist healthcare professionals in both clinical decision-making and the future management of individuals with concussions. More specifically, the minimal symptom provocation in healthy athletes provides normative values that can be used for comparison with the responses of individuals with concussion. This is particularly relevant because symptom provocation may signal incomplete recovery and lack of readiness for individuals to return to sport.

The MET has shown promise in its pilot application with healthy athletes, effectively demonstrating the capacity to induce cardiovascular exertion without significant symptom provocation. The MET emerges as an innovative tool that is widely accessible and cost-effective, and may enhance concussion management by integrating cardiovascular stress, cognitive challenges, and coordination tasks with multi-plane movements. This provides a foundation for further validation of the MET and underscores the MET’s potential as a multifaceted measurement instrument in the context of sport-related concussion management.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

The studies involving humans were approved by Health Sciences Research Ethics Board, University of Toronto (protocol #41884). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

KP: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing. ADB: Data curation, Formal analysis, Visualization, Writing – original draft, Writing – review & editing. DR: Conceptualization, Writing – original draft, Writing – review & editing. NR: Writing – original draft, Writing – review & editing. DL: Writing – original draft, Writing – review & editing. MH: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Writing – original draft, Writing – review & editing.